The overal objective of the proposed research project is to use defined in vitro experimental systems to study the relationship between phenotypic variability and neoplastic progression. We will exploit three observations that we have recently made: 1) The rate of phenotypic variability is 3- to 10-fold greater in breast carcinoma cells than in normal breast epithelial cells; 2) The rate of phenotypic variability (RPV) in hepatoma cells can be manipulated, increased or decreased, with environmental factors; 3) A hypothetical model for quantitative control of gene expression was developed that mimics geometric phenotypic variability seen in cultured cells. We plan to establish if the increased RPV in cancer cells is the result of the neoplastic transformation process itself, or if it is due to individual genetic differences in the host. In a human system, we will develop methods for determining RPV for several different markers in various readily available human cells, such as skin fibroblasts, epithelial cells cultured from urine, epithelial cells cultured from breast milk, blood lymphocytes, and/or cells cultured from amnionic fluid. We will use a standardized routine procedure for determining RPV in breast tumor cells and correlate this information with other prognostic factors of breast cancer. We will attempt to develop a method for determining RPV in standard paraffin-embedded tissue sections. In animal systems we will study RPV in relationship to the genetic makeup, nature of lesion (preneoplastic, invasive, metastatic), nature of the transforming agent (e.g. virus, chemicals), target tissue versus other tissues, and embryonic versus adult tissues. In studies on manipulation of cell phenotype, heterogeneity, and RPV, we plan to find ways to reduce the RPV of tumor cells, either reversibly or irreversibly, with the hope of reducing their rate of progression. Quantitative studies will be conducted on the effect of various environmental factors, such as carcinogens, tumor promoters, hormones, epimutagens, and anti-neoplastic drugs, on quantitative phenotypic expression and variability. Using quantitative in situ hybridization, immunoperoxidase and immunofluorescent techniques, we will study variability in albumin content, albumin mRNA, and albumin gene frequency, arrangement, and chromosome location in normal hepatocytes and hepatoma cells with respect to single cell heterogeneity, geometric phenotypic variability, quantitative control, and neoplastic progression.